1. Field of the Invention
This invention relates to a bulb socket for being attached to a lamp house.
2. Description of Prior Art
As shown in FIGS. 5 and 6, a socket casing 50 of one conventional bulb socket is integrally molded of a resin, and includes a tubular socket portion 51 for receiving a bulb, and a tubular connector portion 52 extending from this socket portion.
An outwardly-extending, mounting flange 53 of a larger diameter is formed on an outer peripheral surface of the socket casing 50 at the boundary between the socket portion 51 and the connector portion 52. And engagement projections 54 are formed on the outer peripheral surface of the socket portion. A plate-like finger support 56 is formed on and projected from the outer peripheral surface of the connector portion 52.
For attaching the bulb socket of this construction to a lamp house, the socket portion 51 is passed through a mounting hole 61 formed through a partition wall 60 of the lamp house, with a gasket 62 of an elastic material interposed between the mounting side of the mounting flange 53 and the partition wall, thus compressing the gasket 62 hard, and in this condition the socket is turned by putting the finger on the finger support portion 56, so that the partition wall 60 is held between the engagement projections 54 and the partition wall 60. The gasket 62 is elastically pressed against the partition wall 60 and the mounting flange 53, thereby imparting waterproofness to the interior of the lamp house.
The mounting flange 53, extending over the entire circumference, and the plurality Of engagement projections 54 need to be formed on the outer periphery of this conventional socket casing in axially spaced relation to each other. Therefore, it is difficult to remove the socket casing 50 from a mold in the axial direction, and therefore the socket casing is molded by a molding method in which the socket casing is removed from the mold in a direction perpendicular to the axis thereof, which mold can be split into halves in the axial direction.
As a result, as shown in an exaggerated manner in FIGS. 5 and 6, axially-extending, linear protuberances, called parting lines P, are formed respectively on upper and lower portions of the outer periphery of the socket casing 50. These raised parting lines P extend across a press surface of the mounting flange 53 which is pressed against the gasket 62, and therefore the gasket 62 can not be held in intimate contact with the mounting flange along the parting lines P, thus inviting a problem that the sealing performance achieved by the gasket 62 is affected.
For attaching a bulb to the bulb socket, a mounting groove 63, called a J-slot, is formed in the inner peripheral surface of the socket portion. This J-slot 63 has an axially-extending insertion groove 63a, and an engagement groove 63b extending laterally perpendicularly from a distal end of the insertion groove 63a. One side surface of the engagement groove 63b disposed at the insertion side serves as an engagement portion 63c. In order to form the J-slot 63 having the laterally perpendicularly-extending engagement groove 63b, a complicated molding method as disclosed in Japanese Patent Unexamined Publication No. 61-96684 must be used.
It is therefore an object of the present invention to provide a bulb socket which has a good sealing performance.
It is another object of the invention to provide a bulb socket which can be produced by a mold of a simple construction.